是否有一个Haskell编译器或预处理器使用严格的评估？ [英] Is there a Haskell compiler or preprocessor that uses strict evaluation?

问题描述

我在寻找一个Haskell编译器，默认使用严格的评估，而不是延迟评估。我只是使用OCaml，但Haskell的语法比OCaml更好（和Haskell是纯的，并有很酷的功能，如类型类）。

我真的不想经常在我的程序中加入！ s和 $！。具有开关或预处理器的编译器放入严格性注释将是非常好的。如果有办法在某些地方使用惰性求值，也是有用的，只是为了防止我想要一个无限列表（我可能永远不会）。

请不要试图说服我懒惰的评价更好，我真的需要性能。 IIRC，Simon Peyton Jones甚至说懒惰的评价并不是真的有必要，它主要是为了防止他们使语言不纯。

解决方案

如果你有一个使用严格评估的Haskell编译器，它不会编译Haskell。 Laziness 非严格性是Haskell规范的一部分！

但是，还有其他选择。

• DDC 试图创建一个明确惰性的Haskell变体，它支持破坏性更新，同时保留Haskell的所有其余部分。有一个问题：编译器目前只处于α阶段，尽管它似乎至少是可用的。




• 像其他人一样创建一个预处理器。 p>




• 学习如何使用Haskell正确的方式。如果您可以将测试用例简化为可公开显示的内容，则可以将其发布在 Haskell-Café邮件列表，其中人们对这些关于非严格性影响的问题非常有帮助。

I'm looking for a Haskell compiler that uses strict evaluation by default instead of lazy evaluation. I would just use OCaml, but Haskell's syntax is so much better than OCaml's (and Haskell is pure, and has cool features such as type classes).

I'd really rather not constantly put !s and $!s all over my program. A compiler with a switch or a preprocessor to put in the strictness annotations would be really nice. It would also be helpful if there was a way to use lazy evaluation in certain places too, just in case I want something like an infinite list (I probably never will).

Please do not try to convince me that lazy evaluation is better, I really need the performance. IIRC, Simon Peyton Jones even said that lazy evaluation wasn't really necessary, it was there mostly to prevent them from making the language impure.

解决方案

If you have a Haskell compiler that uses strict evaluation, it doesn't compile Haskell. Laziness Non-strictness is part of the Haskell spec!

However, there are alternatives.

• DDC is an attempt to create an explicitly lazy variant of Haskell which supports things like destructive update whilst retaining all the rest of Haskell's goodness. There is one problem: the compiler is currently only in the α-stage, although it seems to be at least usable.

• Create a preprocessor, as others have done.

• Learn to use Haskell "the right way". If you can simplify your test case down to something which is publicly-displayable, you could post it on the Haskell-Café mailing list, where people are very helpful with these sorts of questions concerning the effects of non-strictness.

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